Bimetallic material for electronic tube applications

ABSTRACT

A BIMETALLIC MATERIAL SUITABLE FOR PARTS UTILIZED IN ELECTRONIC TUBES IS DISCLOSED. THE MATERIAL CONSISTS ESSENTIALLY OF A FIRST METALLIC ALLOY ELEMENT THAT UNDERGOES A FIRST PHASE CHANGE AT A TEMPERATURE WHICH IS BELOW AMBIENT TEMPERATURE AND A SECOND PHASE CHANGE AT AN ELEVATED TEMPERATURE WHICH IS ENCOUNTERED DURING ELECTRONIC TUBE MANUFACTURING. THE FIRST ELEMENT IS METALLURGICALLY BONDED ALONG A COMMON INTERFACE TO A SECOND METALLIC ALLOY ELEMENT THAT DOES NOT UNDERGO PHASE CHANGES WITHIN THE FOREGOING TEMPERATURE RANGES. THE SECOND ELEMENT HAS COEFFICIENT OF EXPANSION WHICH APPROXIMATELY MATCHES THE FIRST ELEMENT AFTER IT HAS UNDEGONE THE PHASE CHANGE AT THE HIGHER TEMPERATURE. THE MATERIAL IS DEFORMED BY A PREDETERMINED AMOUNT TO A PREDETERMINED PATTERN TO ENABLE A CONTACT TO BE MADE WITH ANOTHER ELEMENT OF AN ELECTRONIC TUBE.

United States Patent US. Cl. 29-1955 5 Claims ABSTRACT OF THE DISCLOSURE A bimetallic material suitable for parts utilized in electronic tubes is disclosed. The material consists essentially of a first metallic alloy element that undergoes a first phase change at a temperature which is below ambient temperature and a second phase change at an elevated temperature which is encountered during electronic tube manufacturing. The first element is metallurgically bonded along a common interface to a second metallic alloy element that does not undergo phase changes within the foregoing temperature ranges. The second element has coefficient of expansion which approximately matches the first element after it has undergone the phase change at the higher temperature. The material is deformed by a predetermined amount to a predetermined pattern to enable a contact to be made with another element of an electronic tube.

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a continuation-in-part of copending patent application Ser. No. 206,124, filed Dec. 8, 1971, now Pat. No. 3,743,485 and assigned to the same assignee as the present invention.

BACKGROUND OF THE INVENTION Field of the Invention This invention relates to bimetals. More particularly, it relates to bimetallic materials that are capable of being deformed a predetermined amount upon heating or cooling.

Conventional bimetals are used to yield a deflection of the composite with a change in temperature by utilizing the dilferences in the coefificients of thermal expansion of two alloys which are metallurgically bonded along a common interface. As can be appreciated, these bimetallic materials deflect throughout a given temperature range. Therefore, such bimetallic elements are useful in indicating the temperature over a range of temperatures.

In certain applications, however, it would be beneficial to have a material which could be placed in a location, subjected to a particular temperature upon which the material would deflect a desired amount and thereafter retain the same amount of deflection until subjected to a second particular temperature.

Many parts within the electronic tubes are now fabricated from resilient metal that is shaped to provide a contact with another member of the tube. Such members are difficult to assemble and also are susceptible to fatigue. These spring-like parts rely upon the resilient nature of the metal similar to a spring.

It is believed, therefore, it is an advancement in the art to provide a material capable of being manufactured into a part which will deform only during the manufacture of the tube to produce a pattern thus providing a positive contact with and remain in predetermined pattern even though the tube is subsequently stored under relatively cold atmospheric conditions.

3,832,148 Patented Aug. 27, 1974 OBJECTS AND SUMMARY OF THE INVENTION It is an object of this invention to provide a bimetallic material capable of controlled deformation.

It is a further object of this invention to provide a bimetallic material having a constant deformation over a predetermined temperature range.

It is an additional object of this invention to provide a bimetallic material which can be heated to reach a first preselected temperature thereby producing a controlled deformation which deformation remains constant until a second preselected temperature is reached at which the material is converted to its original shape.

These and other objects are achieved in the present claimed embodiment comprising a first metallic alloy element which converts from the martensite phase to the austenite phase between about 300 C. and 400 C. which temperature is encountered during the manufacture of a tube and converts from austenite to martensite at below about -40 C. The first element is metallurgically bonded to a second metallic alloy element along a common interface. The second element does not undergo a phase change between about i60 and 500 C. and has essentially the same coefficient of expansion as the said first element when said first element is in the austenite phase.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention, together with other and further objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the above description of some of the aspects of the invention.

The bimetallic materials of this invention employ as a first element an alloy which undergoes a phase change at a first preselected temperature, referred to herein as T at which temperature the metal undergoes a pronounced change in volume. This phase will remain until the temperature reaches a second preselected temperature, referred to herein as T at which the metal is transformed to the original phase. The first element is metallurgically bonded to a second metallic element having a single phase over a temperature range which overlaps and is broader than the range between T and T The second element has substantially the same coeflicient of thermal expansion as the first element between T and T By a phase change, as used herein, it is meant that the original phase is at least partially replaced by a new phase. The bimetallic material of this invention can be fabricated by different methods to yield a bimetallic material which will function in numerous ways.

To provide a bimetallic material of this invention that undergoes the deformation upon being heated to T the coefficient of expansion of the second element is matched with that of the first element after the phase change occurs upon heating to T 'In this instance T is not numerically equal to T in the previous described embodiment but merely refers to the temperature where the first element undergoes a first phase change. The numerical values will depend upon the particular alloy. In this embodiment the first element is transformed upon reaching T from martensite to austenite and the deformation of the bimetallic material of this invention occurs. The deformation will remain relatively constant until the temperature of the material reaches T at which time the first element is appreciably transformed to a martensite phase and the deformation is eliminated.

In most instances, it will be desired to use a first element having one phase change temperature below about 40 C. and another phase change temperature, above about 200 C. The first and second elements should have substantially the same coefficients of thermal expansion during the time the material is deformed and between T and T that is, the ditferences in the average coefiicients of expansion between the two elements when in the deformed state and between T and T should not exceed about 5 p.p.m./ C.

In electronic tube manufacture, the temperature of parts such as contactors, dart or spring clips, shadow mask support means, getter supports, snubbers and the like reach temperatures of at least 300 C. Thus, these parts can be fabricated from the materials of this invention. The part is fabricated in a shape that upon reaching a temperature of from about 300 to 400", depending upon the particular part, the first metallic alloy element of the bimetallic material undergoes a phase change from martensite to austenite; thus causing the part to deform to a predetermined pattern to provide the desired degree of contact. The predetermined pattern remains since the coeflicients of expansion of the two materials are matched under all tube operating conditions and since there is no conversion of the first element to the martensite phase until the temperature of the part reaches at least -40 C. or lower.

A bimetallic material consisting of a first metallic alloy element of an alloy containing iron and nickel, more particularly from 29 to 34% nickel and the balance iron and utilizing either steel, 35 to 52% nickel, iron alloy or a stabilized 33% nickel iron alloy can be utilized to fabricate the foregoing parts. The level of nickel in the first alloy can be adjusted to change the transformation tem perature depending upon the actual temperature the particular part reaches during electronic tube manufacture.

While there has been shown and described what are at present considered and preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

What is claimed is:

1. A bimetallic material consisting essentially of a first metallic alloy element which undergoes a change from martenite to austenite at a temperature between about 300 and 400 C. and a change from austenite to martensite at a temperature below about --40 C., said first element being metallurgically bonded along a common interface to a second metallic alloy element being single phase in the temperature range of from about '-60 C. to above about 500 C, and having substantially the same coetficient of thermal expansion when said first element is in the austenite phase.

2. A material according to Claim 1 wherein said first metallic element is a nickel-iron alloy.

3. A material according to Claim 2 wherein said alloy contains 29 to 34% nickel.

4. A material according to Claim 1 wherein said second element is selected from the group consisting of steel, 35 to 52% nickel-iron alloy and a carbon or alloy stabilized 33% nickel-iron alloy.

5. A material according to Claim 2 wherein said second element is selected from the group consisting of steel, 35 to 52% nickel-iron alloy and a carbon or alloy stabilized 33% nickel-iron alloy.

References Cited UNITED STATES PATENTS 3,581,366 6/1971 Gottlieb et a1. 29-195.5 3,625,663 12/1971 Majesko 29-1955 3,712,799 l/1973 Ornstein 29--196.l 3,743,485 7/1973 Gottlieb et al. 29-195.5 3,765,846 10/1973 Gottlieb ct a1. 29195.5

WALTER R. SATTERFIELD, Primary Examiner US. Cl. X.R. 148-34 v UNITED STATES PATENT OFF-ICE CERTIFICATE OF CORRECTION Patent No. 3,832,148 Dated August 27, 1974 Inventor(s) Arnold J. Gottlieb and George A. Majesko It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

C01. 4, Claim 1, Line 4 martenite" should read martensite Signed and sealed this 3rd day of December 1974.

(SEAL) Attest:

MCCOY M; GIBSON JR. c. MARSHALL DANN Attesting Officer Commissioner of Patents 

